Chang Shwu-Fen, Yang Li-Ming, Lo Chia-Hsin, Liaw Jia-Horng, Wang Li-Hsuan, Lin Shwu-Jiuan
Department of Medicinal Chemistry, College of Pharmacy, Taipei Medical University, Taiwan, Republic of China.
J Nat Prod. 2008 Jan;71(1):87-92. doi: 10.1021/np070468g. Epub 2008 Jan 5.
Preparative-scale fermentation of isosteviol ( ent-16-oxobeyeran-19-oic acid) (1) with Mucor recurvatus MR 36, Absidia pseudocylindrospora ATCC 24169, and Aspergillus niger BCRC 32720 afforded nine known metabolites ( 2, 3, 5-10, and 14) and nine new metabolites ( 4, 11-13, and 15-19). The reactions involved stereoselective introduction of OH groups at positions C-1, -6, -7, -9, -11, -12, -15, and -17 as well as further ketonization at the C-1 and C-7 positions. The structures of the metabolites were established on the basis of 1D and 2D NMR and IR supported by HRFABMS. GRE (glucocorticoid response element)- and ARE (androgen response element)-mediated luciferase reporter gene assays were used to screen for the biological activities of 1 and its metabolites. Compounds 7, 13, 16, and 18 showed significantly enhanced GRE-mediated luciferase activity, but at levels less than that induced by either methylprednisolone or dexamethasone. On the other hand, compounds 3, 4, 12, 13, 14, and 18 showed significant effects on ARE-mediated luciferase activity; in particular, 3, 12, 14, and 18 were more active than testosterone.
采用弯孢毛霉MR 36、假圆柱状犁头霉ATCC 24169和黑曲霉BCRC 32720对异甜菊醇（对映-16-氧代贝壳杉烷-19-酸）（1）进行制备规模发酵，得到了9种已知代谢产物（2、3、5 - 10和14）和9种新的代谢产物（4、11 - 13以及15 - 19）。这些反应涉及在C-1、-6、-7、-9、-11、-12、-15和-17位立体选择性引入羟基，以及在C-1和C-7位进一步酮化。代谢产物的结构基于一维和二维核磁共振以及红外光谱，并得到高分辨快原子轰击质谱的支持得以确定。采用糖皮质激素反应元件（GRE）和雄激素反应元件（ARE）介导的荧光素酶报告基因检测法对1及其代谢产物的生物活性进行筛选。化合物7、13、16和18显示出GRE介导的荧光素酶活性显著增强，但低于甲泼尼龙或地塞米松诱导的水平。另一方面，化合物3、4、12、13、14和18对ARE介导的荧光素酶活性有显著影响；特别是，3、12、14和18比睾酮更具活性。
